Ongoing and planned studies include evaluation of populations exposed to benzene, chlorinated solvents, organochlorines, disinfection byproducts. polycyclic aromatic hydrocarbons, arsenic, formaldehyde, diesel exhaust, coal combustion products, and selected pesticides. On-going case-control studies include stomach, esophagus, brain, bladder, renal cell, thyroid, prostate and breast cancer. The study of NHL and other hematological malignancies is a particularly important area of focus. NHL is one of the most common malignancies occurring among immunosuppressed individuals, including those with HIV/AIDS and those receiving iatrogenic immunosuppression to prevent graft rejection following transplantation. We are conducting a large case-control study of NHL, a large cohort study of populations exposed to agricultural agents including those that increase risk of NHL, and cohort and molecular epidemiology studies of populations exposed to chemicals that have been associated with increased risk of NHL including benzene and trichloroethylene. These studies will examine the role of genetic, occupational, environmental, and lifestyle risk factors, as well as viral exposures including HIV, and analyze interactions between them to provide further insight into the pathogenesis of NHL.